Home – Home – Jornals – Avtometriya 2016 number 5

The possibility of improving the parameters of semiconductor integrated circuits by replacing the silicon layer in a metal-insulator-semiconductor transistors by a material with higher mobility of charge carriers. It is shown that for the totality of properties, germanium is best suited for this purpose. Recent developments in this area made in different laboratories both in Russia and abroad are discussed.

A new technological route for fabricating Ge based metal-oxide-semiconductor (MOS) transistors has been developed based on materials research of dielectric layer compositions. Unwanted impurities were encapsulated by using the gate-first process and a modified thermal GeO₂ layer with increased viscosity at the interface with the Ge substrate. Increasing the density of the oxide layer near germanium interaction with the deposited Si₃N₄ film hindered diffusion of impurities into adsorbed by the substrate surface into the transistor channel. This made it possible to increase the electron mobility in the MIS transistor and prevent its decrease at cryogenic temperatures.

Nanowire field-effect transistors are high-sensitivity sensor elements intended for the qualitative and quantitative analyses of biological and chemical substances. Optimization of the sensor operation is one of the key ways of increasing their sensitivity. An algorithm for choosing the operation mode of sensors based on silicon-on-insulator transistors is proposed which provides their maximum response during conductivity monitoring in the detection of target particles.

The current-voltage characteristics (CVC) of PbSnTe:In films with a tin content of x ≈ 0.29 at helium temperatures under conditions of unipolar injection from contacts and restriction by a spatial charge in a magnetic field of up to 4 T have been studied. Analysis of the CVC has shown that the observed CVC features change as the magnetic field is increased from 0 to 4 T. The relationship between these features and the presence of a multilevel system of traps located in the band-gap zone is validated.

Negative differential resistance in an UV laser InGaN/GaN diode is demonstrated. Switching between the lower and upper branches of the S-shaped current-voltage characteristic leads to a change in the optical radiation power by six orders of magnitude as the current is increased from 3 to 15 mA.The occurrence of a negative differential resistance is explained by superlinear injection of charge carriers of the same sign into a high-resistivity InGaN quantum well.

This paper describes the design and characteristics of the three-spectrum multielement photodetector with a sensitivity range from 0,6 to 12,0 μm, which consists of three lines of photodetectors with the sensitivity ranges from 0,6 to 0,9, from 3 to 5, and from 8 to 12 μm. The methods for manufacturing the lines, the photodetecting device in general, and its photoelectric characteristics are described.

This paper presents a brief review of experimental works in the field of quantum cryptography and quantum key generation by means of single photons in the atmospheric and fiber quantum communication lines. This paper given the description of two experimental devices for quantum key generation, which were designed at the Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences. The results of the study of the dependence of the speed of the quantum key generation on the average number of photons $\mu$ in the laser pulse are given. There is a discrepancy between theory and experiment found for $\mu>0.3$, which may be due to nonzero probability of occurrence of multiphoton pulses in the quantum transmission, which are detected by the single photon detectors as single-photon pulses. When it comes to sieving the quantum key, the cases with simultaneous triggering of several single-photon detectors are ignored because the measurement result is not determined.

This paper presents the review of studies of photoelectric properties of the PbSnTe:In films obtained by molecular beam epitaxy and the photosensitive structures of the far infrared and submillimeter ranges based on these films. The parameters of this type of multielement photodetectors and the detectors based on doped semiconductors and superconductors. Ruled (2 x 128 elements) and matrix (128 x 128 elements) multielement PbSnTe:In based photodetectors with a sensitive edge equal to ~22 m and an operating temperature of T ≤ 16 K are implemented. In the background-free conditions, the power equivalent to the noise reached MES ≤ 10^-18 W/Hz^0.5 for T = 7 K for the radiation source of the absolute black body type at T_ABB = 77 K. The submillimeter region of the spectrum had sensitivity to laser radiation with a wavelength λ ≤ 205 μm and the value of MES ≤ 10^-12 W/Hz^0.5 without optimization of the layout design of the photosensitive member and minimization of the measurement circuit noise. The directions of the development of PbSnTe:In based radiation detectors are considered.

This paper describes the model of Poisson's composite compound distribution for photon statistics with regard to their grouping in the Fock, thermal, and many other states. The method of generating functions is used to calculate the distribution of probabilities, moments, and correlation functions. The parameters of the conditional states arising from the subtraction of photons by splitting the beam are determined. The problem of state reconstruction through quadrature quantum measurements is considered. The research is aimed at developing high-precision methods for generating and controlling optical quantum states.

Experiments and simulations are performed to study the formation of silicon nanocrystals (Si-NC) in multilayer structures with alternating ultrathin layers of SiO₂ and amorphous hydrogenized silicon (α-Si:H) during high-temperature annealing. The effect of annealing on the transformation of the structure of the α-Si:H layers is studied by methods of high-resolution transmission electron microscopy, Raman spectroscopy, and photoluminescence. The conditions and kinetics of Si-NC formation are analyzed by the Monte Carlo technique. The type of the resultant crystalline silicon clusters is found to depend on the thickness and porosity of the original amorphous silicon layer located between the SiO₂ layers. It is shown that an increase in the thickness of the α-Si layer in the case of low porosity leads to the formation of a percolation silicon cluster instead of individual Si nanocrystals.

The phase and elemental compositions of GeSi heterostructures deposited on non-refractory substrates are analyzed by using a non-destructive express technique, i.e., the Raman spectroscopy. It is shown that application of pulsed laser annealing allows one to vary the elemental composition and size of nanocrystals formed from solid alloys of germanium and silicon.

The formation of an absorption layer on the Si(111) surface under conditions of sublimation at temperatures of 1000-1100 °C and subsequent quenching at T = 750 °C is studied by methods of in situ superhigh-vacuum reflection electron microscopy and ex situ atomic force microscopy. The distribution of the concentration of adatoms on an extrawide (~60 μm) atomically smooth terrace is determined for the first time, and the diffusion length x_s = 31 ± 2 μm at T = 1000 °C is obtained. The analysis of the temperature dependence of the equilibrium concentration of adatoms near a monatomic step allows pioneering measurements of the energy necessary for the adatom to pass from the step to the terrace E_ad ≈ 0,68 eV. Based on these results, the energy parameters for some atomic processes on the Si(111) surface are estimated.

A Monte Carlo grid model is proposed to describe the formation of semiconductor nanostructures by the vapor-liquid-crystal growth mechanism. This model is used to simulate the growth of GaAs nanostructures by the method of droplet epitaxy in the temperature range from 500 to 600 K in As₂ flows with intensity of 0.005-0.04 ML/s. The morphology of the resultant structures is demonstrated to depend on the growth parameters. Etching of the GaAs substrate by a gallium droplet is studied. The ranges of temperature and As flow rates necessary for the formation of GaAs nanorings are determined. The conditions of the formation of single and double concentric rings are analyzed.

A method is presented to be used in a computational experiment aimed at studying the internal structure of nano-mesoscopic objects, i.e., conducting subsystems and quantum phenomena in solid submicron objects, which demonstrate an individual behavior of low-temperature resistance.